How we get data

Task goals

• Identify the different ways data can be gathered: observation, questionnaire, survey, or census.
• Explain the difference between a sample and a census, and identify the population being studied in a given context.
• Explain why a sample should be selected at random, and why increasing sample size generally improves reliability.
• Classify how a piece of data was collected — by counting, by measuring, or by observing and placing it in a category — and justify the classification.
• Choose and justify an appropriate data-collection method for a given real-world investigation scenario.